U.S. patent application number 17/066145 was filed with the patent office on 2021-03-11 for polymer composition and methods using said polymer composition to manufacture ophthalmic lens.
This patent application is currently assigned to ESSILOR INTERNATIONAL. The applicant listed for this patent is ESSILOR INTERNATIONAL. Invention is credited to John BITEAU, Robert VALERI.
Application Number | 20210072425 17/066145 |
Document ID | / |
Family ID | 1000005227383 |
Filed Date | 2021-03-11 |
![](/patent/app/20210072425/US20210072425A1-20210311-C00001.png)
![](/patent/app/20210072425/US20210072425A1-20210311-C00002.png)
![](/patent/app/20210072425/US20210072425A1-20210311-C00003.png)
![](/patent/app/20210072425/US20210072425A1-20210311-C00004.png)
![](/patent/app/20210072425/US20210072425A1-20210311-C00005.png)
United States Patent
Application |
20210072425 |
Kind Code |
A1 |
VALERI; Robert ; et
al. |
March 11, 2021 |
Polymer Composition and Methods Using Said Polymer Composition to
Manufacture Ophthalmic Lens
Abstract
The present invention proposes a polymer composition of
manufacturing ophthalmic lens by polymerization of polymerizable
composition wherein the shrinkage phenomenon is minimized. The
polymerizable composition comprised two different categories of
monomers which are able during crosslinking to control and limit
said chemical shrinkage. The present invention comprises also
ophthalmic lens obtained from said polymer composition using a
manufacturing process of casting or additive manufacturing.
Inventors: |
VALERI; Robert; (Dallas,
TX) ; BITEAU; John; (Dallas, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ESSILOR INTERNATIONAL |
Charenton-le-Pont |
|
FR |
|
|
Assignee: |
ESSILOR INTERNATIONAL
Charenton-le-Pont
FR
|
Family ID: |
1000005227383 |
Appl. No.: |
17/066145 |
Filed: |
October 8, 2020 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
15106617 |
Jun 20, 2016 |
|
|
|
PCT/IB2013/003007 |
Dec 20, 2013 |
|
|
|
17066145 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29K 2069/00 20130101;
G02C 7/022 20130101; B33Y 10/00 20141201; B29C 64/135 20170801;
B29C 37/0025 20130101; B29D 11/00442 20130101; B33Y 70/00 20141201;
G02B 1/041 20130101; B29L 2011/0016 20130101; B29D 11/0048
20130101; G02B 1/043 20130101; B29C 64/112 20170801; B29D 11/00028
20130101; B33Y 80/00 20141201; B29K 2063/00 20130101; B29K
2105/0014 20130101 |
International
Class: |
G02B 1/04 20060101
G02B001/04; B29D 11/00 20060101 B29D011/00; B33Y 10/00 20060101
B33Y010/00; B29C 64/112 20060101 B29C064/112; B29C 64/135 20060101
B29C064/135; B33Y 70/00 20060101 B33Y070/00; B33Y 80/00 20060101
B33Y080/00; B29C 37/00 20060101 B29C037/00 |
Claims
1.-21. (canceled)
22. A method of manufacturing an ophthalmic lens, wherein a
polymerizable composition is manufactured by an additive
manufacturing process, wherein the polymerizable composition
comprises at least: a monomer or oligomer (A) comprising at least
one reactive group further defined as an epoxy, thioepoxy,
epoxysilane, (meth)acrylate, thio(meth)acrylate, vinyl, urethane,
thiourethane, isocyanate, mercapto, or alcohol group, wherein the
monomer or oligomer (A) shrinks during polymerization; and a
monomer (B) comprising at least a non-aromatic cyclic group wherein
during polymerization the cyclic group opens and reacts with
another molecule of monomer (B) and/or with a reactive group of
monomer or oligomer (A), wherein the monomer (B) expands during
polymerization, wherein the additive manufacturing process
comprises: 1) constituting voxels of the polymerizable composition;
2) increasing viscosity of at least the constituted voxel; 3)
optionally inter-diffusing at least a voxel, wherein viscosity is
increased, into another voxel, through a physical and/or a chemical
treatment; and 4) repeating 1), 2), and, optionally 3) in a same or
different order according to reactive groups involved in monomer
(A) and monomer (B) of the polymerizable composition to form a
transparent ophthalmic lens.
23. The method of claim 22, wherein each voxel comprises the same
polymerizable composition comprising at least a monomer or oligomer
(A) and a monomer (B).
24. The method of claim 22, wherein voxels comprise different
polymerizable compositions such that some voxels comprise a first
polymerizable composition comprising monomer or oligomer (A) and
monomer (B), and some other voxels comprise a different
polymerizable composition comprising a monomer or oligomer (A') and
monomer (B'), wherein (A') is chemically different than (A), and
(B') is chemically different than (B).
25. The method of claim 22, wherein increasing the viscosity
comprises: a crosslinking process, which could be initiated by
cationic reaction, by free radical reaction or by condensation
reaction by applying activating light or thermal treatment to
liquid composition; an evaporation process; and/or a process
consisting of submitting a liquid composition to a temperature
which is below the temperature used at the deposition step of the
voxel.
26. The method of claim 25, wherein increasing the viscosity
comprises evaporation of a solvent comprised in a liquid
composition.
27. The method of claim 22, wherein inter-diffusing comprises:
spontaneous inter-diffusion; and/or induced inter-diffusion, via a
process comprising exposure to radiation, mechanical agitation,
decrease of molecular mass of voxel, and/or exposure to a
solvent.
28. The method of claim 22, further comprising applying at least
one post-treatment to improve homogenization of the transparent
ophthalmic lens.
29. The method of claim 28, wherein the post-treatment step
comprises at least one of: a crosslinking process initiated by
cationic reaction, free radical reaction, or a condensation
reaction by applying activating light or thermal treatment to the
liquid composition; an annealing process; and/or a drying process
by thermal treatment or solvent extraction.
30. The method of claim 22, wherein the additive manufacturing
process comprises a 3D printing process or a stereolithography
process.
31. The method of claim 22, further comprising: adding at least one
functional coating and/or a functional film, on at least one face
of the ophthalmic lens.
32. The method of claim 31, wherein the functionality of the
coating and/or the film is further defined as impact resistance,
anti-abrasion, anti-soiling, anti-static, anti-reflective,
anti-fog, anti-rain, self-healing, polarization, tint,
photochromic, and/or selective wavelength filter further defined as
an absorption filter, a reflective filter, an interferential filter
and/or a combination thereof.
33. The method of claim 22, wherein the transparent ophthalmic lens
is further defined as a blank lens, a semi-finished lens, a
finished lens, or a lens adapted to a see-through head-mounted
display.
34. The method of claim 33, wherein: the transparent ophthalmic
lens is further defined as an afocal, unifocal, bifocal, trifocal,
or progressive lens; the ophthalmic lens is adapted for mounting to
either a traditional frame comprising two distinctive ophthalmic
lenses, one for a right eye and one for a left eye, or to a mask,
visor, helmet sight or goggle, wherein one ophthalmic lens faces
simultaneously a right and a left eye; and/or the ophthalmic lens
has a round geometry or a geometry fitted to the geometry of an
intended frame.
35. The method of claim 22, wherein monomer or oligomer (A)
comprises from 99% to 1% by weight of the total weight of polymer
composition and monomer (B) comprises from 99% to 1% by weight of
the total weight of the polymer composition.
36. The method of claim 22, wherein monomer (B) is a cyclic group
that is monocyclic or polycyclic, substituted or unsubstituted,
without aromaticity properties, and further defined as a cyclic
sulfate, spiroorthoester, bicyclic-ortho ester, cyclic carbonate,
spiroorthocarbonate, bicyclic ketal lactone, and/or combination
thereof.
37. The method of claim 22, wherein at least part of a reactive
group of monomer or oligomer (A) reacts with at least part of a
reactive group of monomer (B) after the opening of the cyclic
group, to form a copolymer of monomer (A) and (B) during
polymerization process.
38. The method of claim 22, wherein: the reactive group of monomer
or oligomer (A) reacts only with a reactive group of another
molecule of monomer or oligomer (A) to form a homopolymer (A)
during polymerization process; and the reactive group resulting
from the opening of the cyclic part of monomer (B) reacts only with
the reactive group of another molecule of monomer (B) to form a
homopolymer (B) during polymerization process.
39. The method of claim 22, wherein the polymerizable composition
comprises an amount of monomer (B) to reduce the shrinkage of the
composition to less than 5%.
40. The method of claim 22, wherein the polymerizable composition
further comprises a polymerization initiator defined as a
photo-initiator, a thermal initiator, or a combination thereof.
41. The method of claim 22, wherein the polymerizable composition
comprises at least one further additive defined as a co-initiator,
inhibitor, dye, pigment, UV absorber, fragrance, deodorant, surface
active agent, surfactant, binder, antioxidant, optical brightener,
and/or anti-yellowing agent.
Description
TECHNICAL FIELD
[0001] The present invention relates to polymer composition of
manufacturing ophthalmic lens, to methods of manufacturing an
ophthalmic lens comprising said polymer composition and to
ophthalmic lens obtained by said methods.
BACKGROUND
[0002] Plastic ophthalmic lenses are well known and have a common
usage. Today there are two main categories of plastic lenses, the
first wherein plastic represents a thermoplastic polymer, and the
second wherein plastic represents a thermoset polymer resulting
from the polymerization of a polymerizable composition comprising
monomer and/or oligomer which are able to polymerize under actinic
or thermal activation to form a polymer.
[0003] Usually in the ophthalmic field, thermoplastic lenses are
obtained through an injection process and thermosetting lenses are
obtained through a casting process. Thermosetting polymer
represents a polymer network formed by the chemical reaction of
monomers, at least one of which has two or more reactive groups per
molecule (that means a functionality equal to or higher than two),
and that presents in relative amounts such that a gel is formed as
a particular conversion during the synthesis. In a symbolic form,
it may be stated that a threshold polymer is obtained by the
homopolymerization of an Af molecule (wherein f superior or equal
to 2, and represents the number of functional/reactive group per
molecule A), or the polymerization of an Af molecule by reaction
with a Bg molecule, and they are present in a particular ratio such
that a gel will be formed.
[0004] Then polymer network is formed in an irreversible way, the
synthesis of a thermosetting polymer is carried out to produce
final material with the desired shape. Therefore, polymer and final
shaping are performed in the same process. This represents a
disadvantage in the ophthalmic industry. In fact, to manufacture a
lens of thermosetting material, monomers used to obtaine such
material are casted between two molds having the required surface
geometries. The number of combination of surface geometries needed
in the ophthalmic lens is too broad to have one specific mold for
one specific lens in accordance with the prescription of a wearer,
and/or in accordance with the geometry of the frame wherein said
lens will be mounted. So in the traditional process, ophthalmic
lens are manufactured through a subtractive process, wherein
firstly the lens is casted has a round shape as a semi-finished
lens or finished lens, and then this round shape submit various
steps like surfacing and edging to provide a final lens (with less
polymer material than the initial lens round shape) adapted to the
prescription of a wearer and adapted to be mounted to a frame
choice by said wearer. So part of initial thermosetting material is
loss and this consumption of material represent economical and
environment issue.
[0005] Additive Manufacturing methods and devices have become
well-known in various industries for production of parts and
products formerly manufactured using subtractive manufacturing
techniques, such as traditional machining. Application of such
manufacturing methods has not been systematically applied.
[0006] By additive manufacturing it means a manufacturing
technology as defined in the international standard ASTM 2792-12,
which mentions a process of joining materials to make objects from
3D model data, usually layer upon layer, as opposed to subtractive
manufacturing methodologies, such as traditional machining.
[0007] The additive manufacturing method may be selected in, but is
not limited to, the list consisting of stereolithography, mask
stereolithography or mask projection stereolithography, polymer
jetting, scanning laser sintering or SLS, scanning laser melting or
SLM, fused deposition modeling or FDM.
[0008] Additive manufacturing technologies comprise processes which
create objects by juxtaposition of volume elements according to a
pre-determined arrangement that can be defined in a CAD (Computer
Aided Design) file. Such juxtaposition is understood as the result
of sequential operations such as building a material layer on top
of a previously obtained material layer and/or juxtaposing a
material volume element next to a previously obtained volume
element.
[0009] The primary advantage of this technique is its ability to
create almost any shape or geometric feature. Advantageously, using
such additive manufacturing methods provides much more freedom
during the determining step.
[0010] So this is an object of the invention to provide a polymer
composition to manufacture transparent ophthalmic lens by
polymerization of a polymerizable composition comprising at least a
monomer or oligomer (A) and a monomer (B), said composition being
able to be used to a traditional casting process using two molds or
to an additive manufacturing process, more specifically to a
stereolithography, mask stereolithography, mask projection
stereolithography, or polymer jetting, using a 3D printing
device.
[0011] Another disadvantage of polymerizable composition used
usually to traditional ophthalmic industry is linked to the
shrinkage phenomenon. At a general knowledge shrinkage could be
defined as a reduction in the size of a part after it has changed
from a liquid state to a solid state. So for polymer composition
obtained by polymerization of polymerizable composition, during the
curing cycle, the thermoset undergoes the residual deformation and
stresses due to shrinkage of matrix. This shrinkage may have a
thermal and/or chemical origin. The chemical shrinkage is a direct
consequence of crosslinking of the thermosetting polymer.
[0012] When polymerizable composition shrink, materials of the
objects can change their fundamental properties. The shrinkage can
cause change in geometry and shrinking of a part of the object will
also induce internal stress buildup. Objects having an internal
stress buildup tend toward a more relaxed state by changing their
geometry. This is especially problematic when manufacturing
products, such as ophthalmic lenses. In particular, it is critical
that ophthalmic lenses be transparent and that their geometric
configuration be maintained throughout manufacturing. Typically the
geometric configuration of an ophthalmic lens comprises a first
surface and a second surface that can have complex curvatures. Any
shrinkage or distortion of these curvatures could affect the
optical property of the lens.
[0013] In traditional manufacturing processes, such as mold
casting, it's known that all resins shrink during polymerization,
and this is usually compensated for by the mold design. In
traditional subtractive manufacturing processes that involve a
post-processing step, the subtractive manufacturing steps
compensate for any shrinkage. However, to avoid the time-consuming
step of post-processing used in subtractive manufacturing, it's
preferable for the geometry of the object not to change from
deposition to final cure. In one known solution, a software program
such as CAD, has been used to predict or model the amount of
shrinkage that a product would undergo that is produced by additive
manufacturing. This solution is complex because it must be adapted
to each article shape and material. Thus, there exists a need to
reduce or control shrinkage of an ophthalmic lens during additive
manufacturing while maintaining the geometric stability of the
ophthalmic lens. The physical constitution of voxels in additive
manufacturing technologies classically uses physical means to
induce geometry variations in the voxels during the fabrication
process. The physical means may include introducing light and/or
thermal variations. Unfortunately, said means typically generate
dimensional shrinkage at the scale of individual voxels, and also
macroscopic stress building at the scale of the object produced by
the additive manufacturing process.
[0014] These dimensional changes at the individual voxel scale or
from the collective effect during voxel assembly, including stress
build up, which can directly impact the optical characteristics of
the final object as well the ability of the final object to modify
an optical wavefront propagation in a controlled and deterministic
fashion. For ophthalmic lenses, such dimensional changes alter the
final prescription associated with said ophthalmic lenses, causing
a severe detriment when the prescription is supposed to be
individualized to a particular wearer.
[0015] So it is an object of the invention to provide a polymer
composition to manufacture an ophthalmic lens by polymerization of
polymerizable composition wherein the shrinkage phenomenon is
minimized. The polymerizable composition comprised 2 different
categories of monomers which are able during crosslinking to
control and limit said chemical shrinkage.
SUMMARY OF THE INVENTION
[0016] The present invention proposes a polymer composition to
manufacture a transparent ophthalmic lens characterized in that it
is obtained by polymerization of a polymerizable composition
comprising at least: [0017] a monomer or oligomer (A) comprising at
least a reactive group selected from epoxy, thioepoxy, epoxysilane,
(meth)acrylate, thio(meth)acrylate, vinyl, urethane, thiourethane,
isocyanate, mercapto, and alcohol, wherein said monomer (A) shrinks
during polymerization; [0018] a monomer (B) comprising at least a
non-aromatic cyclic group wherein during polymerization said cyclic
group opens and reacts with another molecule of monomer (B) and/or
with a reactive group of monomer (A), and [0019] wherein said
monomer (B) expands during polymerization.
[0020] To the polymer composition, monomer or oligomer (A) is
present from 99% to 1% by weight of the total weight of
polymerizable composition and monomer (B) is present from 1% to 99%
by weight of the total weight of polymerizable composition.
[0021] Monomer (B) possesses a cyclic group which could be
monocyclic, or polycyclic, substituted or unsubstituted, without
aromaticity properties, said cyclic group being selected from
cyclic sulfates, spiroorthoesters, bicyclic-ortho esters, cyclic
carbonates, spiroorthocarbonates, bicyclic ketal lactones, and
combinations thereof.
[0022] In an embodiment of the invention at least part of reactive
group of monomer or oligomer (A) reacts with at least part of
reactive group of monomer (B) after the opening step of the cyclic
group, to form a copolymer of monomer (A) and (B) during
polymerization process.
[0023] In another embodiment, reactive group of monomer or oligomer
(A) reacts only with reactive group of another molecule of monomer
or oligomer (A) to form a homopolymer (A) during polymerization
process; and reactive group resulting from the opening of the
cyclic part of monomer (B) reacts only with reactive group of
another molecule of monomer (B) to form a homopolymer (B) during
polymerization process; and no phase separation appears between
homopolymer (A) and homopolymere (B) to the resulting polymer
composition of the invention.
[0024] Advantageously, the ratio of monomer (B) to monomer or
oligomer (A) is increased proportionally with the increasing number
of reactive groups present in each monomer or oligomer (A).
[0025] The polymer composition according to the invention comprises
an amount of monomer (B) to reduce the shrinkage of said polymer
composition to less than 5%, preferably less than 2% and most
preferably around 0%.
[0026] The polymer composition of the invention is polymerized in
the presence of a polymerization initiator or catalyst. The polymer
composition may also comprise various additives. According to the
invention the polymerization is carried out photochemically or by
heating.
[0027] It is also an object of the invention to provide a method of
manufacturing an ophthalmic lens characterized in that the
polymerizable composition according to the invention and comprising
at least a monomer or oligomer (A) and a monomer (B), as mentioned
hereinbefore, is cast between two molds having the required surface
geometries and polymerization is then carried out, optionally
followed by annealing.
[0028] In another embodiment, the invention comprises also a method
of manufacturing an ophthalmic lens characterized in that the
polymer composition according to the invention is manufactured by
an additive manufacturing process comprising the following
steps:
[0029] /1/ constituting voxels of said polymerizable composition
comprising at least a monomer or oligomer (A) and a monomer (B) as
mentioned hereinbefore;
[0030] /2/ increasing viscosity of at least a said constituted
voxel;
[0031] /3/ optionally inter-diffusing at least a voxel, wherein
viscosity is increased, into another voxel, through a physical
and/or a chemical treatment;
[0032] /4/ repeating steps /1/, /2/, /3/ in the same order as cited
or in a different order according to reactive groups involved in
monomer (A) and monomer (B) of said polymerizable composition to
form a transparent ophthalmic lens; and
[0033] /5/ optionally applying at least a post-treatment to improve
homogenization of the transparent ophthalmic lens.
[0034] After deposition of a first voxel (or group of voxels), a
first treatment increases the viscosity of the voxels such that
they substantially remain where deposited and have sufficient
cohesion to support later-deposited voxels. After deposition of a
second voxel (or group of voxels), monomer and/or oligomer from the
first voxel (or group of voxels) diffuse into the second voxel (or
group of voxels) either spontaneously or under application of a
second treatment. The second treatment can optionally polymerize or
increase the viscosity of the resulting combination of voxels.
These steps can be repeated for several sequential depositions. An
optional, final treatment, such as photo-polymerization, can occur
after each deposition of the voxels.
[0035] In accordance with the invention, and depending on the
additive manufacturing technology implementation, said three mains
actions may be achieved voxel-to-voxel, line-to-line,
layer-by-layer, and/or after all desired layers have been formed to
produce said three-dimensional transparent ophthalmic lens.
[0036] The transparent ophthalmic lens manufactured by a method in
accordance of any previous embodiments may further be treated to
obtain an ophthalmic lens with at least one added value. Then in
accordance with this, the invention comprises a method comprising
further step(s): [0037] adding at least a functional coating and/or
a functional film, on at least one face of the ophthalmic lens;
[0038] the functionality of said coating and/or said film being
selected from impact-resistance, anti-abrasion, anti-soiling,
anti-static, anti-reflective, anti-fog, anti-rain, self-healing,
polarization, tint, photochromic, and selective wavelength filter
which may be obtained through an absorption filter, a reflective
filter, an interferential filter or a combination thereof; [0039]
said functionality may be added by at least one process selected
from dip-coating, spin-coating, spray-coating, vacuum deposition,
sputtering, transfer process or lamination process.
[0040] The transparent ophthalmic lens, manufactured in accordance
with an embodiment of the present invention, represents an
ophthalmic lens selected from blank lens, semi-finished lens,
finished lens, and lens adapted to see-trough "Head-Mounting
Display" (HMD). By Head mounting display it is understood a device
able to be mounted on the head of a wearer, and comprising an
optical imager for shaping light beams coming from an electronic
and optical system that generates light beams from an electronic
signal, the system being of the miniature screen, laser diode, or
light-emitting diode (LED) type; the optical imager directing light
beams towards the eye of the wearer so as to enable an information
content to be used.
[0041] Said transparent ophthalmic lens, may also represent a lens
selected from afocal (or no-corrective, or plano), unifocal,
bifocal, trifocal, and progressive lens, said ophthalmic lens being
able to be mounted either to traditional frame comprising two
distinctive ophthalmic lenses, one for the right eye and one for
the left eye, or to mask, visor, helmet sight or goggle, wherein
one ophthalmic lens facing simultaneously the right and the left
eyes, and said ophthalmic lens may be produced with traditional
geometry as a circle or may be produced to be fitted to the
geometry to the frame intended. When said ophthalmic lens is
dedicated to be mounted to a see-trough "HMD", said lens may be
corrective or afocal, and may be placed on the front face and/or on
the rear face of the optical imager of the HMD. When the ophthalmic
lens is placed on the front face and on the rear face of the
optical imager, it means that the optical imager is inserted inside
said ophthalmic lens.
[0042] Transparent ophthalmic lens obtained from a method of at
least one mentioned embodiment is also an object of the present
invention.
[0043] More details relating to the various embodiments of the
invention will be described in the detailed description part of the
invention, without any limitation to the general method described
hereinbefore.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0044] The words or terms used herein have their plain, ordinary
meaning in the field of this disclosure, except to the extent
explicitly and clearly defined in this disclosure or unless the
specific context otherwise requires a different meaning.
[0045] If there is any conflict in the usages of a word or term in
this disclosure and one or more patent(s) or other documents that
may be incorporated by reference, the definitions that are
consistent with this specification should be adopted.
[0046] The words "comprising," "containing," "including," "having,"
and all grammatical variations thereof are intended to have an
open, non-limiting meaning. For example, a composition comprising a
component does not exclude it from having additional components, an
apparatus comprising a part does not exclude it from having
additional parts, and a method having a step does not exclude it
having additional steps. When such terms are used, the
compositions, apparatuses, and methods that "consist essentially
of" or "consist of" the specified components, parts, and steps are
specifically included and disclosed. As used herein, the words
"consisting essentially of," and all grammatical variations thereof
are intended to limit the scope of a claim to the specified
materials or steps and those that do not materially affect the
basic and novel characteristic(s) of the claimed invention.
[0047] The indefinite articles "a" or "an" mean one or more than
one of the component, part, or step that the article
introduces.
[0048] Whenever a numerical range of degree or measurement with a
lower limit and an upper limit is disclosed, any number and any
range falling within the range is also intended to be specifically
disclosed. For example, every range of values (in the form "from a
to b," or "from about a to about b," or "from about a to b," "from
approximately a to b," and any similar expressions, where "a" and
"b" represent numerical values of degree or measurement) is to be
understood to set forth every number and range encompassed within
the broader range of values, and including the values "a" and "b"
themselves.
[0049] Terms such as "first," "second," "third," etc. may be
assigned arbitrarily and are merely intended to differentiate
between two or more components, parts, or steps that are otherwise
similar or corresponding in nature, structure, function, or action.
For example, the words "first" and "second" serve no other purpose
and are not part of the name or description of the following name
or descriptive terms. The mere use of the term "first" does not
require that there be any "second" similar or corresponding
component, part, or step. Similarly, the mere use of the word
"second" does not require that there be any "first" or "third"
similar or corresponding component, part, or step. Further, it is
to be understood that the mere use of the term "first" does not
require that the element or step be the very first in any sequence,
but merely that it is at least one of the elements or steps.
Similarly, the mere use of the terms "first" and "second" does not
necessarily require any sequence. Accordingly, the mere use of such
terms does not exclude intervening elements or steps between the
"first" and "second" elements or steps, etc.
[0050] As used herein, "Additive Manufacturing" means manufacturing
technology as defined in the international standard ASTM 2792-12,
describing a process of joining materials to make 3-D solid objects
from a 3-D digital model. The process is referred to as "3-D
printing" or "materials printing" since successive layers are laid
down atop one another. Printing materials include liquids, powders,
and sheet materials, from which series of cross-sectional layers
are built. The layers, which correspond to the virtual cross
sections from the CAD model, are joined or automatically fused to
create the solid 3-D object. Additive Manufacturing includes, but
is not limited to, manufacturing methods such as stereolithography,
mask stereolithography, mask projection stereolithography, polymer
jetting, scanning laser sintering (SLS), scanning laser melting
(SLM), and fused deposition modelling (FDM). Additive Manufacturing
technologies comprise processes which create 3-D solid objects by
juxtaposition of volume elements or particles according to a
pre-determined arrangement, typically defined in a CAD (Computer
Aided Design) file. Juxtaposition is understood as sequential
operations including building one material layer on top of a
previously built material layer, and/or positioning a material
volume element next to a previously deposited material volume
element.
[0051] One such additive manufacturing method employs a printer
head such as in an ink-jet or polymer-jet printer that deposits
discrete units (voxels) of a composition onto a substrate or
previously deposited voxel. The voxels are typically deposited as
layers, with successive layers inter-diffused and converted to a
geometrically stable voxel composition. In jet printing a critical
step is maintaining voxel shape. The voxel shape is then converted
to a homogenous solid by UV or thermal curing, for example. These
printing processes are particularly compatible with the polymer
composition of the present invention.
[0052] Another method involves a pool or bath of polymerizable
composition as a curable liquid. A selected cross-section of a
layer of the polymerizable composition is cured, such as by
exposure to UV radiation. An additional layer of the curable liquid
is then constituted or deposited onto the first layer, and the
process is gradually repeated, building-up the desired
three-dimensional solid element. This technology is well known as
stereolithography and its derivatives.
[0053] As used herein, "voxel" means a volume element. A voxel is a
distinguishable, geometric shape which is part of a
three-dimensional space. As used herein, "voxel" can refer to an
individual element which, in combination with other voxels, defines
an intermediate element which could be a layer of within the space.
Additionally, the term "voxel," as used herein, can apply to an
intermediate element which is part of the three-dimensional space.
That is, a single voxel can comprise a layer of the
three-dimensional space, more particularly when the additive
manufacturing technology used is based on stereolithography
technologies. A particular voxel may be identified by x, y, and z
coordinates of a selected point of geometry of the shape, such as a
corner, centre, etc., or by other means known in the art.
[0054] Within the terms of reference of the invention, an
ophthalmic lens is understood to be transparent when the
observation of an image through said ophthalmic lens is perceived
with no significant loss of contrast, that is, when the formation
of an image through said ophthalmic lens is obtained without
adversely affecting the quality of the image. This definition of
the term "transparent" can be applied, within the terms of
reference of the invention, to all objects qualified as such in the
description.
[0055] In the present invention, the wording "constitutes a voxel"
and its derivatives could be understood like: [0056] deposit a
droplet of polymerizable composition to a substrate, through an
inkjet head of an ink-jet printer; in this case the additive
manufacturing technology used is polymer jetting and the droplet
represents a voxel. [0057] apply a polymerizable composition as a
thin layer to a surface of a bath and performe selective
polymerization of said composition; in this case the additive
manufacturing technology used is stereolithography
[stereolithography, mask stereolithography or mask projection
stereolithography] and the layer represents a voxel.
[0058] As used herein, polymerization/polymerizing/polymerizable
refers to a chemical reaction that produces bonding of two or more
monomers and/or oligomers to form a polymer. Polymerization and all
grammatical variations include photo-polymerizable and/or
thermo-polymerizable compositions. Photo-polymerizable means
polymerization which occurs by exposing a composition to activating
light. Thermo-polymerizable means polymerization which occurs by
exposing the composition to a variation of temperature.
[0059] As used herein, curing refers to a chemical process of
converting a monomer or a oligomer into a polymer of higher molar
mass and then into a network.
[0060] As used herein, "monomer" and/or "oligomer" refer to a
chemical compound comprising at least a reactive group able to
react to activating light, and/or temperature in the presence of an
initiator. More details relating to "reactive group" being involved
will be described latter in the present specifications.
[0061] As used herein "activating light" refers to actinic
radiation and visible light. Activating light may affect a chemical
change. Activating light may include ultraviolet light (e.g., light
having a wavelength between about 280 nm to about 400 nm), actinic
light, visible light or infrared light. Generally, any wavelength
of light capable of affecting a chemical change may be classified
as activating. Chemical changes may be manifested in a number of
forms. A chemical change may include, but is not limited to, any
chemical reaction that causes a polymerization to take place.
[0062] As used herein, an initiator represents a photo-initiator or
a thermo-initiator.
[0063] A photo-initiator represents a molecule employed alone or in
a chemical system (involving two or more molecules) that absorbs
light and forms reactive initiating species. Then by absorption of
light, a photo-initiator generates reactive species (ion or
radical) and initiates a chemical reaction or transformation.
[0064] As used herein, a co-initiator represents a molecule as part
of a chemical system which does not absorb light but, nevertheless,
participates in the production of the reactive species.
[0065] The polymer composition according to the invention can also
contain additives used conventionally in compositions intended for
manufacturing ophthalmic elements, in standard proportions, namely,
inhibitors, dyes, UV absorbers, fragrances, deodorants, surface
active agents, surfactants, binders, antioxidants,
optical-brigthner and anti-yellowing agents.
[0066] As used herein, "inter-diffuse," and derivatives, means
movement of at least an ion, molecule, portion of a molecule, or
portion of a polymer chain, from the space occupied by one voxel
into the space occupied by a juxtaposed, physically contacting,
voxel. Inter-diffusion can occur spontaneously or be induced by
mechanical, physical, or chemical treatment. For example, a
mechanical treatment includes agitation, such as by exposure to
ultra-sonic energy, high-frequency vibratory device, etc., which
promote mixing at the voxel boundaries. Macro-diffusion is a
mechanical method wherein the voxels are blended or "smeared" by
table vibrations, especially where such vibrations occur at the
time of deposition, resulting in intimate voxel-to-voxel contact.
An exemplary physical treatment includes a thermal treatment by
exposure to heat, infra-red, microwave, etc., radiation. A thermal
treatment increases temperature above the glass-liquid transition
point (Tg) of the high viscosity domain in the voxels and promotes
inter-diffusion. An exemplary chemical treatment includes a
chemical reaction between reactive species of composition. The
molecular mass of the polymers present in the voxels can be
reduced, such as by two-pathway chemistries or reversible
reactions, to promote inter-diffusion.
[0067] The polymer composition according to the invention comprises
at least a monomer (B), said monomer (B) expands during
polymerization. Generally, an expanding monomer is one that
exhibits expansion in volume during ring opening polymerization.
Thus, the monomeric volume of the composition may be maintained
during polymerization or may be only minimally changed during
polymerization or may be only negligibly changed during
polymerization. In addition, the volume after polymerization of a
composition comprising an expanding monomer is either maintained
(e.g., with near zero shrinkage) or only minimally reduced or only
negligibly reduced. The shrinkage of a composition containing an
expanding monomer may be less than about 5% or less than about 4%
or less than about 3% or less than about 2% or most preferably
around 0%. The monomers (B) disclosed herein are capable of
expanding their volume after polymerization.
[0068] Monomers (B) comprised at least a non-aromatic cyclic group
such as cyclic carbonates or bicyclic monomers with fused rings
(having at least one carbon atom in common) that maintain or expand
their volume during polymerization due to an opening of strained
rings. Bicyclic expanding monomers exhibit a double ring opening
during polymerization, such that for every shift from a van der
Waals bond to a covalent bond, which occurs during polymerization,
there are two covalent bonds that are broken. This is in contrast
with conventional monomers (or oligomers) that shrink during
polymerization, which leads to a negative change in volume, which
is sometimes quite significant. Conventional monomers or oligomers
also undergo a one-to-one replacement of one van der Waals
attraction with one covalent bond during polymerization.
[0069] Catalysis (polymerization) of an expanding monomer is
generally initiated by a Lewis acid (e.g., cationic-induced ring
opening or anionic-induced ring opening) or a free-radical
initiating agent. Catalysis often occurs in the absence of a
solvent. A solvent may be included depending on the selection of
any additional monomer(s) or oligomer(s) present in the initial
polymerizable composition. Optionally, a reaction promoter, capable
of accelerating polymerization, may be added (e.g., polyol) to the
initial polymerizable composition. Polymerization of expanding
monomers (B) may also be initiated in the presence of light, such
as visible light or ultraviolet (UV) light; hence, said expanding
monomers are often photopolymerizable. In addition, many expanding
monomers (B) are temperature sensitive, such that the temperature
during polymerization directly affects the degree of expansion.
[0070] In accordance with the invention monomer (B) comprises a
non-aromatic cyclic group, which may be monocyclic or polycyclic,
substituted or unsubstituted. By monocyclic group it is understood
a cycle carbon chain comprising from 5 to 12 atoms to said chain,
wherein 1 to 4 carbon atom could be replaced by a group selected
from O, N, CO, S, SO, or SO.sub.2 and wherein 1 to 3 single
carbon-carbon bond of the cycle chain could be replaced by
carbon-carbon double bonds. By polycyclic group it is understood a
group comprising 1, 2 or 3 cycles, each cycle being from 3 to 8
members, each cycle being fused together or bond together by at
least one common atom, wherein 1 to 6 carbon atom of the polycyclic
chain may be replaced by a group selected from O, N, CO, S, SO, or
SO.sub.2 and wherein 1 to 4 single carbon-carbon bond of the
polycyclic chain may be replaced by carbon-carbon double bonds.
Such monocyclic group is represented for example by the following
structure: cyclopentyl, cyclohexyl, cycloheptyl, azirine, oxyrane,
thiiranes, oxetane, oxelane, imidazoline, imidazolidine,
morpholine, piperazine, piperidine, pyrazolidine, pyrrolidine, and
the like. Such polycyclic group may be for example derivative of
quinuclidine, oxaspiro[4,5]decane, 3,9-dioxaspiro[5,5]undecane,
dispiro[4.2.4.2]tetradecane, spiro[4.4]nona-2,7-diene, . . . .
Preferentially, in accordance with the invention, Monomer (B)
represents a fused bicyclic rings, and more particularly wherein
said ring of the bicyclic have at least one common atom (spiro
structure), each ring contains at least one atom of another element
than carbon, and the ring do not open in a symmetrical manner. For
example, an oxygen atom in one ring may from a carbonyl group while
the corresponding oxygen in the other ring would form an ether
group.
[0071] Monocyclic or polycyclic group of monomer (B) may be
unsubstituted or comprised from 1 to 6 substituents, identical or
different, independently of each other, selected from
C.sub.1-C.sub.6 alkyl, C.sub.1-C.sub.6 alkenyl, C.sub.1-C.sub.6
alkoxy, halo, hydroxy, selected from halogen, --R.sub.a, --OH,
--OR.sub.a, --SH, --SR.sub.a, --NH.sub.2, --NR.sub.aR.sub.a1,
--CO--R.sub.a, --CO.sub.2R.sub.a1, wherein R.sub.a and R.sub.a1
identical or different represent a group selected from
C.sub.1-C.sub.10 alkyl wherein a carbon-carbon bond may be replaced
by at least one carbon-carbon double bond, and/or from 1 to 3
carbon atom may be replaced by an oxygen atom, a sulphur atom or a
carbonyl group.
[0072] Suitable monomer (B), as described herein, will include
preferentially, but are not limited to, cyclic sulfates,
spiroorthoesters, bicyclic-ortho esters, cyclic carbonates,
spiroorthocarbonates, norbornene spiroorthocarbonates, bimethylene
spiroorthocarbonates and bicyclic ketal lactones.
[0073] A cyclic sulfate will have the general structure, as
provided below, before ring opening (25) and after ring opening
(26, 27).
##STR00001##
[0074] A cyclic carbonate will have the general structure, as
provided below, before (20) ring opening and after (21, 22) ring
opening.
##STR00002##
[0075] A bicyclic-ortho ester will have the general structure, as
provided below, before (left) a double ring opening and after
(right) a double ring opening.
##STR00003##
[0076] A spyro-ortho ester will have the general structure, as
provided below, before (left) a double ring opening and after
(right) a double ring opening.
##STR00004##
[0077] Polymerization with expansion in volume can be achieved with
spiroorthocarbonate monomers through a double ring-opening process
wherein two bonds are cleaved for each new bond formed.
[0078] Monomer or oligomer (A) of the polymerizable composition to
provide the polymer composition in accordance with the invention,
comprises at least a reactive group selected from epoxy, thioepoxy,
epoxysilane, (meth)acrylate, thio(met)acrylate, vinyl, urethane,
thiourethane, isocyanate, mercapto and alcohol. We will now
describe in more details list of monomer and/or oligomer that may
be used as monomer/oligomer (A) in the present invention.
[0079] Monomers/oligomer (A) comprising at least an epoxy/thioepoxy
reactive group are classified as either aromatic (such as bisphenol
A and F epoxies) or aliphatic. Aliphatic epoxies are lower in
viscosity. Aliphatic epoxies can be both completely saturated
hydrocarbons (alkanes) or can contain double or triple bonds
(alkenes or alkynes). They can also contain rings that are not
aromatic. Epoxy may be also monofunctional or polyfunctional, and
such epoxy may be from the family of alkoxysilane epoxy.
[0080] Non-alkoxysilane polyfunctional epoxy monomers may be
selected from the group consisting of diglycerol tetraglycidyl
ether, dipentaerythritol tetraglycidyl ether, sorbitol polyglycidyl
ether, polyglycerol polyglycidyl ether, pentaerythritol
polyglycidyl ether such as pentaerythritol tetraglycidyl
ethertrimethylolethane triglycidyl ether, trimethylolmethane
triglycidyl ether, trimethylolpropane triglycidyl ether,
triphenylolmethane triglycidyl ether, trisphenol triglycidyl ether,
tetraphenylol ethane triglycidyl ether, tetraglycidyl ether of
tetraphenylol ethane, p-aminophenol triglycidyl ether,
1,2,6-hexanetriol triglycidyl ether, glycerol triglycidyl ether,
diglycerol triglycidyl ether, glycerol ethoxylate triglycidyl
ether, Castor oil triglycidyl ether, propoxylated glycerine
triglycidyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol
diglycidyl ether, neopentyl glycol diglycidyl ether,
cyclohexanedimethanol diglycidyl ether, dipropylene glycol
diglycidyl ether, polypropylene glycol diglycidyl ether,
dibromoneopentyl glycol diglycidyl ether, hydrogenated bisphenol A
diglycidyl ether, (3,4-Epoxycyclohexane) methyl
3,4-epoxycylohexylcarboxylate and mixtures thereof.
[0081] The monoepoxysilanes are commercially available and include,
for example, beta-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane,
(gamma-glycidoxypropyltrimethoxysilane),
(3-glycidoxypropyl)-methyl-diethoxysilane, and
gamma-glycidoxy-propylmethyldimethoxysilane. These commercially
available monoepoxysilanes are listed solely as examples, and are
not meant to limit the broad scope of this invention. Specific
examples of the alkyltrialkoxysilane or tetraalkoxysilane suitable
for the present invention include methyltrimethoxysilane,
ethyltrimethoxysilane, phenyltrimethoxysilane.
[0082] Monomers/oligomers (A) of the invention may comprise
(meth)acrylate or thio(meth)acrylate reactive group. As used in the
present invention the term acrylate and acrylic referred to the
same chemical functionality. The word "meth" in two brackets as
"(meth)" associated to the term acrylate, specifies that relating
to a molecule or to a family of molecules the acrylate function
H.sub.2C.dbd.CHC(O)-- could have a methyl group at .quadrature.
position of the ethylene function like
H.sub.2C.dbd.C(CH.sub.3)C(O)--.
[0083] (Meth)acrylates can be monofunctional, difunctional,
trifunctional, tetrafunctional, pentafunctional, and even
hexafunctional. Typically, the higher the functionality, the
greater is the crosslink density. (Meth)acrylates have slower
curing than the acrylates.
[0084] The two, three, four or six (meth)acrylic functional groups
is selected from the group consisting of pentaerythritol
triacrylate, pentaerythritol tetraacrylate, tetraethyleneglycol
diacrylate, diethyleneglycol diacrylate, triethyleneglycol
diacrylate, 1,6-hexanediol di(meth)acrylate, tripropylene glycol
diacrylate, dipropyleneglycol diacrylate, ethyleneglycol
dimethacrylate, trimethylolethane triacrylate, trimethylolmethane
triacrylate, trimethylolpropane triacrylate, trimethylolpropane
trimethacrylate, 1,2,4-butanetriol trimethacrylate,
tris(2-hydroxyethyl) isocyanurate triacrylate, di-trimetholpropane
tetraacrylate, ethoxylated pentaerythritol tetraacrylate,
triphenylolmethane triacrylate, trisphenol triacrylate,
tetraphenylol ethane triacrylate, 1,2,6-hexanetriol triacrylate,
glycerol triacrylate, diglycerol triacrylate, glycerol ethoxylate
triacrylate, ethylene glycol diacrylate, 1,4-butanediol diacrylate,
1,4 butanediol dimethacrylate, neopentyl glycol diacrylate,
cyclohexanedimethanol diacrylate, dipropylene glycol diacrylate,
polypropylene glycol diacrylate dipentaerythritol hexaacrylate,
polyester hexaacrylate, sorbitol hexaacrylate, and fatty
acid-modified polyester hexaacrylate, and is most preferably
dipentaerythritol hexaacrylate.
[0085] Among monomer and/or oligomer comprising this reactive
group, we can mention the monomer corresponding to the above
formula.
##STR00005##
In which R1, R2, R' and R'' represent, independently of one
another, a hydrogen atom or a methyl radical, Ra and Rb, which are
identical or different, each represent an alkyl group having 1 to
10 carbon atoms, and m and n are integers wherein m+n is comprised
between 2 to 20 inclusive.
[0086] Among the monomers particularly recommended in the
compositions according to the invention, of
2,2-di(C2-C10)alkyl-1,3-propanediol 2x-propoxylate di(meth)acrylate
and 2,2-di(C2-C10)alkyl-1,3-propanediol 2x-ethoxylate
di(meth)acrylate, like for example
2-ethyl-2-n-butyl-1,3-propanediol 2x-propoxylate dimethacrylate.
(Meth)acrylic monomers as mentioned above and their process of
preparation are disclosed in the document WO-95/11219. This kind of
monomer is able to be polymerized by photopolymerization techniques
or mixed photopolymerization and thermal polymerization
techniques.
[0087] Advantageously the composition comprising this (meth)acrylic
monomer can comprise other monomer(s) polymerizable by a radical
route, and presenting one or more (meth)acrylate functional groups
and/or one or more allyl groups. Mention may be made, among these
monomers, of poly(methylene glycol) mono- and di(meth)acrylates,
poly(ethylene glycol) mono- and di(meth)acrylates, poly(propylene
glycol) mono- and di(meth)acrylates, alkoxypoly(methylene glycol)
mono- and di(meth)acrylates [sic], alkoxypoly(ethylene glycol)
mono- and di(meth)acrylates [sic] and poly(ethylene
glycol)-poly(propylene glycol) mono- and di(meth)acrylates. These
monomers are disclosed, inter alia, in the document U.S. Pat. No.
5,583,191.
[0088] Mention may be made, among monomers comprising a
(meth)acrylate functional group and an allyl group, of
tri(propylene glycol) di(meth)acrylate, poly(ethylene glycol)
dimethacrylate [sic] (for example, poly(ethylene glycol-600)
dimethacrylate, poly(propylene glycol) dimethacrylate [sic] (for
example, poly(propylene glycol-400) dimethacrylate), bisphenol A
alkoxylate dimethacrylate [sic], in particular bisphenol A
ethoxylate and propoxylate dimethacrylate [sic] (for example,
bisphenol A 5-ethoxylate dimethacrylate, bisphenol A 4,8-ethoxylate
dimethacrylate and bisphenol A 30-ethoxylate dimethacrylate).
Mention may also be made, among the monofunctional monomers, of
aromatic mono(meth)acrylate oligomers, and, among the trifunctional
monomers, of tri(2-hydroxyethyl)iso-cyanurate triacrylate,
trimethylolpropane ethoxylate acrylate and trimethylolpropane
propoxylate acrylate.
[0089] The polymerizable composition according to the invention and
comprising such (meth)acrylate monomer and/or oligomer, also
comprises a system for initiating the polymerization. The
polymerization initiating system can comprise one or more thermal
or photochemical polymerization initiating agents or alternatively,
preferably, a mixture of thermal and photochemical polymerization
initiating agents.
[0090] Generally, the initiating agents are used in a proportion of
0.01 to 5% by weight with respect to the total weight of monomers
present in the composition. As indicated above, the composition
more preferably simultaneously comprises a thermal polymerization
initiating agent and a photoinitiator.
[0091] Among monomer/oligomer (A) comprising thio(meth)acrylate as
reactive group, the present invention can notably use functional
monomers of mono(thio)(meth)acrylate or mono- and di(meth)acrylate
type bearing a 5- to 8-membered heterocycle consisting of hydrogen,
carbon and sulphur atoms and having at least two endocyclic sulphur
atoms. Preferably, the heterocycle is 6- or 7-membered, better
still 6-membered. Also preferably, the number of endocyclic sulphur
atoms is 2 or 3. The heterocycle can optionally be fused with a
substituted or unsubstituted C5-C8 aromatic or polycyclanic ring,
preferably a C6-C7 ring. When the heterocycle of the functional
monomers contains 2 endocyclic sulphur atoms, these endocyclic
sulphur atoms are preferably in positions 1-3 or 1-4 of the
heterocycle. According to the invention, the monomer is preferably
also a thio(meth)acrylate monomer. Lastly, the monomers according
to the invention preferably have molar masses of between 150 and
400, preferably 150 and 350 and better still between 200 and 300.
Example of such monomers is described in the document U.S. Pat. No.
6,307,062 which is incorporated by reference.
[0092] Advantageously the polymerizable composition comprising such
thio(meth)acrylate monomers may comprise a co-monomer.
[0093] Among the co-monomers which can be used with the monomers
(A) of (thio)(meth)acrylate type for polymerizable compositions
according to the invention, mention may be made of mono- or
polyfunctional vinyl, acrylic and methacrylic monomers.
[0094] Among the vinyl co-monomers which are useful in the
compositions of the present invention, mention may be made of vinyl
alcohols and vinyl esters such as vinyl acetate and vinyl butyrate.
The acrylic and methacrylic co-monomers can be mono- or
polyfunctional alkyl (meth)acrylate co-monomers and polycyclenic or
aromatic mono(meth)acrylate co-monomers. Among the alkyl
(meth)acrylates, mention may be made of styrene,
.alpha.-alkylstyrenes such as .alpha.-methyl styrene, methyl
(meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate,
isobutyl (meth)acrylate or difunctional derivatives such as
butanediol dimethacrylate, or trifunctional derivatives such as
trimethylolpropane trimethacrylate.
[0095] Among the polycyclenic mono(meth)acrylate co-monomers,
mention may be made of cyclohexyl (meth)acrylate, methylcyclohexyl
(meth)acrylate, isobornyl (meth)acrylate and adamantyl
(meth)acrylate.
[0096] Co-monomers which may also be mentioned are aromatic
mono(meth)acrylates such as phenyl (meth)acrylate, benzyl
(meth)acrylate, 1-naphthyl (meth)acrylate, fluorophenyl
(meth)acrylate, chlorophenyl (meth)acrylate, bromophenyl
(meth)acrylate, tribromophenyl (meth)acrylate, methoxyphenyl
(meth)acrylate, cyanophenyl (meth)acrylate, biphenyl
(meth)acrylate, bromobenzyl (meth)acrylate, tribromobenzyl (meth)
acrylate, bromobenzylethoxy(meth)acrylate,
tribromobenzylethoxy(meth)acrylate and phenoxyethyl
(meth)acrylate.
[0097] The crosslinking process which is particularly suitable for
polymerizable composition based on thio(meth)acrylate alone or in
combination with at least one co-monomer, as defined hereinbefore,
are photochemical polymerization or a combination of a
photochemical polymerization and a thermal condensation reaction. A
recommended polymerization process is photochemical polymerization
via ultraviolet radiation and preferably UV-A radiation. Thus, the
composition also contains photo-initiators and/or condensation
catalysts. Preferably photo-initiators and/or thermal catalyst, are
present in proportions of from 0.001 to 5% by weight relative to
the total weight of the composition, and even more preferably from
0.01 to 3.5%. The photo-initiators which can be used in composition
according to the invention are, in particular,
2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-hydroxycyclohexyl
phenyl ketone, 2,2-dimethoxy-1,2-diphenyl-1-ethanone and
alkylbenzoin ethers.
[0098] Vinyl ether group presents as reactive group to monomer or
oligomer (A) is also suitable. Example of such compound comprising
this functionality are ethyl vinyl ether, propyl vinyl ether,
isobutyl vinyl ether, cyclohexyl vinyl ether, 2-ethyl hexyl vinyl
ether, butyl vinyl ether, ethylenglycol monovinyl ether,
diethyleneglycol divinyl ether, butane diol divinyl ether, hexane
diol divinyl ether, cyclohexane dimethanol monovinyl ether
[0099] Among the preferred polyisocyanate or isothiocyanate
monomers or oligomers (A) suitable in accordance with the present
invention, there may be cited tolylene diisocyanate or
diisothiocyanate, phenylene, diisocyanate or diisothiocyanate,
ethylphenylene diisocyanate or diisothiocyanate, isopropyl
phenylene diisocyanate or diisothiocyanate, dimethylphenylene
diisocyanate or diisothiocyanate, diethylphenylene diisocyanate or
diisothiocyanate, diisopropylphenylene diisocyanate or
diisothiocyanate, trimethylbenzyl triisocyanate or
triisothiocyanate, xylylene diisocyanate or diisothiocyanate,
benzyl triiso(thio)cyanate, 4,4'-diphenyl methane diisocyanate or
diisothiocyanate, naphthalene diisocyanate or diisothiocyanate,
isophorone diisocyanate or diisothiocyanate, bis(isocyanate or
diisothiocyanate methyl) cylcohexane, hexamethylene diisocyanate or
diisothiocyanate, and dicyclohexylmethane diisocyanate or
diisothiocyanate.
[0100] Among monomer or oligomer (A) comprising a mercapto reactive
group, the preferred polythiol monomers and/or oligomers suitable
in accordance with the present invention, there may be cited
aliphatic polythiols such as pentaerythritol tetrakis
mercaptopropionate, 1-(1'-mercaptoethylthio)-2,3-dimercaptopropane,
1-(2'-mercapropylthio)-2,3-dimercaptopropane,
1-(3'-mercapropylthio)-2,3-dimercaptopropane,
1-(4'-mercabutylthio)-2,3-dimercaptopropane,
1-(5'-mercapentylthio)-2,3-dimercaptopropane,
1-(6'-mercahexylthio)-2,3-dimercaptopropane, 1,
2-bis-(4'-mercaptobutylthio)-3-mercaptopropane,
1,2-bis-(5'-mercaptopentylthio)-3-mercaptopropane,
1,2-bis-(6'-mercaptohexylthio)-3-mercaptopropane,
1,2,3-tris(mercaptomethylthio)propane,
1,2,3-tris-(3'-mercaptopropylthio)propane,
1,2,3-tris-(2'-mercaptoethylthio)propane,
1,2,3-tris-(4'-mercaptobutylthio)propane,
1,2,3-tris-(6'-mercaptohexylthio)propane, methanedithiol,
1,2-ethandithiol, 1,1-propanedithiol, 1,2-propanedithiol,
1,3-propanedithiol, 2,2-propanedithiol,
1,6-hexanethiol-1,2,3-propanetrithiol, and
1,2-bis(2'-mercpatoethylthio)-3-mercaptopropane.
[0101] Photo-initiator may be used alone or in a mixture of two or
more compounds, or as a combination or two or more compounds like
co-initiators. The choice of photo-initiator is based firstly to
the nature of reactive group(s) of monomer or oligomers (A) and
monomer (B) used in the polymerizable composition and also to the
kinetic of polymerization. Then it is well-known that cationic
curable compositions cure slower than free radically curable
compositions. In term of methods used in accordance with the
various embodiments of the invention, the man skilled in the art
will adapt easily the choice of such photoinitiator.
[0102] Example of Free radical initiator suitable for the present
invention, are listed below, without any limitation: benzophenone,
methyl benzophenone, xanthones, acylphosphine oxide type such as
2,4,6-trimethylbenzoyldiphenyl phosphine oxide,
2,4,6-trimethylbenzoylethoxydiphenyl phosphine oxide,
bisacylphosphine oxides (BAPO), benzoin and benzoin alkyl ethers
like benzoin methyl ether, benzoin isopropyl ether.
[0103] Free radical photo-initiators can be selected also for
example from haloalkylated aromatic ketones such as
chloromethylbenzophenones; some benzoin ethers such as benzoin
methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin
isobutylether ether, benzoin, benzyl, benzyl disulfide;
dialkoxyacetophenones such as diethoxyacetophenone and
.alpha.,.alpha.-dimethoxy-.alpha.-phenylacetophenone,
benzylideneacetophenone, benzophenone, acetophenone; hydroxy
ketones such as
(1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one)
(Irgacure.RTM. 2959 from CIBA), 2,2-di-sec-butoxyacethophenone,
2,2-diethoxy-2-phenyl-acetophenone,
1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure.RTM. 184 from CIBA)
and 2-hydroxy-2-methyl-1-phenylpropan-1-one (such as Darocur.RTM.
1173 sold by CIBA); alpha amino ketones, particularly those
containing a benzoyl moiety, otherwise called alpha-amino
acetophenones, for example 2-methyl
1-[4-phenyl]-2-morpholinopropan-1-one (Irgacure.RTM. 907 from
CIBA), (2-benzyl-2-dimethyl
amino-1-(4-morpholinophenyl)-butan-1-one (Irgacure.RTM. 369 from
CIBA); monoacyl and bisacyl phosphine oxides and sulphides, such as
phenylbis(2,4,6-trimethylbenzoyl)-phosphine oxide (Irgacure.RTM.
819 sold by CIBA); triacyl phosphine oxides; and mixtures
thereof.
[0104] Mention may be made, among the photoinitiators, of in
particular 2,4,6-trimethylbenzoyldiphenyl-phosphine oxide,
1-hydroxycyclohexyl phenyl ketone,
2,2-dimethoxy-1,2-diphenylethane-1-one [sic] and alkyl benzoyl
ethers.
[0105] Cationic photo-initiator comprises notably compounds which
are able to form aprotic acids or Bronstead acids upon exposure to
activating light like UV or visible light. Examples of suitable
cationic photo-initiator, without any limitations are listed below:
aryldiazonium salts, diaryliodonium salts, triarylsulfonium salts,
triarylselenium salts.
[0106] Mention may be made, among the thermal polymerization
initiating agents which can be used in the present invention, of
organic peroxides, inorganic peroxides, or azo initiators. Organic
peroxides can include, but are not limited to, peroxycarbonates,
peroxyesters, dialkylperoxides, diacylperoxide, diperoxyketals,
ketoneperoxides, hydroperoxides, benzoyl peroxide, cyclohexyl
peroxydicarbonate and isopropyl peroxydicarbonate Inorganic
peroxide thermal initiators can include, but are not limited to,
ammoniumpersulfate, potassiumpersulfate, and sodiumpersulfate.
[0107] As used herein, a co-initiator represents a molecule as part
of a chemical system which does not absorb light but, nevertheless,
participates in the production of the reactive species.
Co-initiator is particularly suitable in combination with some
free-radical initiator, like benzophenone which requires a second
molecule, such as an amine, to produce a curable radical. Then,
under UV radiation, benzophenone reacts with a tertiary amine by
hydrogen abstraction, to generate an alpha-amino radical which is
well known to initiate polymerization of (meth)acrylate monomer(s)
and/or oligomer(s)
[0108] Examples of co-initiators are listed below comprise reactive
amine co-initiators commercially available from Sartomer company
under the trade names of CN-381, CN6383, CN-384, and CN-386, where
these co-initiators are monoacrylic amines, diacrylic amines, or
mixture thereof. Other co-initiators include triethylamine,
N-methyldiethanloamine, triethanolamine,
ethyl-4-simethylaminobenzoate, ethyl-2-dimethylaminobenzoate,
n-butoxyethyl-4-dimethylamino benzoate-p-dimethyl amino
benzaldehyde, N,N-dimethyl-p-toluidine, and
octyl-p-(dimethylamino)benzoate.
[0109] In accordance with the invention, advantageous monomers or
oligomer (A) are such presented reactive groups selected from epoxy
and (meth)acrylate. In a preferred embodiment of the invention it
could be judicious to obtain a polymer composition, by
polymerization of polymerizable composition comprising at least a
monomer (B) which is able to expand after polymerization and at
least a monomer or oligomer (A) which is able to present a low
shrinkage. To minimize the shrinkage of a monomer some chemical
modification could be introduced to the chemical structure of such
monomer or oligomer (A) as, for example, an increased chain length,
a low number of double bonds, or a reduced number of reactive
groups like no more than three. Hence, monomers or oligomers (A)
that are highly functionalized such as tetra, penta and
hexaacrylates, have increased double bond density, and experience
higher volume shrinkage, and thus, are not preferred. In one or
more embodiments, monomer or oligomer (A), as described herein, are
generally selected for having the lowest possible functionality
(number of reactive groups), the highest possible molecular weight
(e.g., increased pendant group size); and a low Tg. While many
conventional monomers or oligomers typically undergo a volume
shrinkage of about greater than about 5%, with an average volume
shrinkage of about 10%, or in a range of greater than about 5% to
up to about 14%, the monomer (or oligomer) (A) will exhibit a
volume shrinkage of about 5% or less. The low shrinkage monomer (or
oligomer) (A), by virtue of the characteristics described, are
known to exhibit a reduced shrinkage as compared with a
conventional monomer that does not have one of the characteristics
just described. Examples of such specific monomer (A) include, but
are not limited to, a diacrylate monomer (e.g.,
1,4'-bis{4-[6-(acryloyl)-1-hexyloxy] benzoyloxy}2-t-butylbenzene; a
dimethacrylate monomer (e.g.,
1,4'-bis{4-[6-(methacryloyl)-1-hexyloxy]benzoyloxy}2-t-butylbenzene,
4,4'-bis{4-[6-(methacryloyloxy)hexyloxy]benzoyloxy} diphenylether
(DPEHDMA); and
2-(t-butyl)-1,4-bis-[4-(6-methacryloxy-hexan-1-oxy)-benzoyloxy]-benzen.
In some instances, a monomer (or oligomer) (A) may also be one that
has a methacrylate side group rather than an acrylate side group. A
methacrylate monomer shrinks less than a corresponding acrylate
monomer.
[0110] In accordance to the invention, solvents suitable for the
polymerizable composition are organic solvents, preferentially
polar solvent like methanol, ethanol, propanol, butanol, glycols,
and glycol monoethers. This solvent could be used alone or in
combination. Used of solvent may be particularly relevant to adjust
the viscosity of monomer component (A) and (B), more particularly
when said composition will be processed through an additive
manufacturing process, and more particularly through a jetting
process.
[0111] As mentioned hereinbefore an object of the invention is also
a method of manufacturing an ophthalmic lens from a polymer
composition in accordance with the invention, by a casting process
or by an additive manufacturing process.
[0112] Such casting process and equipment required are for example
well described in the document U.S. Pat. No. 5,662,839. Then such
method consists in a method of manufacturing an ophthalmic lens
from a polymerizable composition in which a mold is assembled
comprising two molding shells and an annular closure member
disposed around said molding shells and defining therewith a
required molding cavity, said mold is filled with polymerizable
composition, and polymerization of said polymerizable composition
is as least started, in which method the operations of assembling
said mold, filling it and at least starting polymerization of said
polymerizable composition are conducted in the same device. In such
method the polymerization may be initiated by thermal
polymerization or by actinic polymerization depending the nature of
monomer or oligomer (A) and monomer (B) comprised to the
polymerizable composition and the associated initiators used.
[0113] In another embodiment the polymer composition of the present
invention is advantageously processed through an additive
manufacturing process. Using this method to manufacturing an
ophthalmic lens presents the advantage to combine the best
optimization of the present invention: shrinkage control, less
consumption of polymer composition, and ability to obtain directly
a ophthalmic lens directly adapted or closely adapted to the
prescription of a wearer and/or shape of frame choice by said
wearer. So it is an entire part of the invention a method of
manufacturing an ophthalmic lens with a high management level of
the polymerization volume shrinkage, and thus geometry control
during the construction of the ophthalmic lens, through a control
of two technical characteristics of the voxel, that means, the
ability to control shrinkage during polymerization, and the ability
to maintain good geometry and optics properties. So more
particularly, the invention proposes a method of manufacturing an
ophthalmic lens wherein the polymerizable composition of the
invention, is manufactured by an additive manufacturing process
comprising the following steps:
[0114] /1/ constituting voxels of said polymerizable composition
comprising at least a monomer or oligomer (A) and at least a
monomer (B);
[0115] /2/ increasing viscosity of at least a said constituted
voxel;
[0116] /3/ optionally inter-diffusing at least a voxel, wherein
viscosity is increased, into another voxel, through a physical
and/or a chemical treatment;
[0117] /4/ repeating steps /1/, /2/, /3/ in the same order as cited
or in a different order according to reactive groups involved in
monomer or oligomer (A) and monomer (B) of said polymerizable
composition to form a transparent ophthalmic lens; and
[0118] /5/ optionally applying at least a post-treatment to improve
homogenization of the transparent ophthalmic lens.
[0119] After constitution of a first voxel (or group of voxels), a
first treatment increases the viscosity of the voxels such that
they substantially remain where deposited and have sufficient
cohesion to support later-deposited voxels. After constitution of a
second voxel (or group of voxels), monomer(s) and/or oligomer from
the first voxel (or group of voxels) diffuse into the second voxel
(or group of voxels) either spontaneously or under application of a
second treatment. The second treatment can optionally polymerize or
increase the viscosity of the resulting combination of voxels.
These steps can be repeated for several sequential depositions. An
optional, final treatment, such as photo-polymerization, can occur
after each deposition of the voxels. As will be understood by those
skilled in the art, the polymerizable compositions may be curable
by differing means, such as differing intensity, dosage, rate,
and/or frequency of light, and or by the presence of different
initiating agents.
[0120] In accordance with the invention, and depending on the
additive manufacturing technology implementation, said three mains
actions (increase viscosity, voxels inter-diffusion, and post
treatment which could be optional) may be achieved voxel-to-voxel,
line-to-line, layer-by-layer, and/or after all desired layers have
been formed to produce the ophthalmic lens.
Constituting voxels, as mentioned to step /1/ of hereinbefore
process, will include at least one of the following: 1) depositing
a voxel as a droplet of polymerizable composition to a substrate,
through an inkjet head of an ink-jet printer; in this case the
additive manufacturing technology used is polymer jetting;
depositing a voxel as performing selective partial polymerization
of a polymerizable composition in a thin layer on a substrate; in
this case the additive manufacturing technology used is
stereolithography [stereolithography, mask stereolithography or
mask projection stereolithography].
[0121] After constitution of the first voxels, it is desirable to
increase the viscosity of monomer(s)/oligomer(s) blend such that
the voxels remain where deposited and have sufficient cohesion that
they can support additionally dispensed voxels. The step consisting
to increase the voxel viscosity comprises a double objective:
firstly to maintain the integrity and the geometry of each voxel
created during the method, secondly to guarantee that each voxel
represents a three dimensional object. This characteristic is
mandatory to be able to control the geometry of the final 3D
ophthalmic lens. The increase in voxel viscosity can be achieved by
processes such as: [0122] a crosslinking process, which could be
initiate by cationic reaction, by free radical reaction or by
condensation reaction by applying activating light or thermal
treatment to polymerizable composition; [0123] an evaporation
process, and more particularly evaporation of solvent comprised
into said polymerizable composition; and [0124] a process
consisting to submit said polymerizable composition to a
temperature which is below the temperature used at the deposition
step of the voxel.
[0125] It is an embodiment of the invention, wherein each step of
increasing viscosity in a method may be identical or different. As
used herein, "viscosity" refers to a fluid's resistance to
deformation. Polymerizable composition, suitable for use in an
additive manufacturing device, in accordance with the invention,
typically presents a viscosity comprised from 40 to 100 cPs at
25.degree. C. In accordance with the method of the present
invention the step of increasing viscosity is able to increase the
initial viscosity of the polymerizable composition from 5 times to
20 times, the final viscosity of the ophthalmic lens manufactured
by said method being more than 50 000 cPs at 25.degree. C.
[0126] Inter-diffusing step(s) can be promoted by processes
selected from: [0127] a spontaneous inter-diffusion; and [0128] an
induced inter-diffusion, which represent a process selected from
the group consisting of exposure to radiation, mechanical
agitation, decrease and exposure to a solvent.
[0129] Exposure to radiation may be realized for example, through
heating, heated convection, infra-red heating, microwave.
[0130] It is anticipated that successful spontaneous
inter-diffusion requires the voxel composition be below a specific
viscosity at ambient or laboratory conditions to result in
"fast-enough" diffusion between juxtaposed voxels for desirable
mechanical and optical properties to be achieved. There is the same
requirement for inter-diffusion between voxel and intermediate
element or between intermediate element(s).
[0131] In accordance with this herein before embodiment it is
understood that each step of inter-diffusing is identical or
different.
[0132] Post-treatment step(s) may be selected from: [0133] a
crosslinking process, which could be initiated by cationic
reaction, by free radical reaction or by condensation reaction by
applying activating light or thermal treatment to polymerizable
composition; [0134] an annealing process; and [0135] a drying
process by thermal treatment or solvent extraction.
[0136] In accordance with this herein before embodiment it is
understood that each step of post-treatment is identical or
different.
[0137] In a specific embodiment of the invention it is possible to
use different polymerizable composition for constituting the
different voxels. By different polymerizable composition it is
understood, that each polymerizable composition comprises at least
a monomer/oligomer (A) and a monomer (B), but said monomer/oligomer
(A) may be different in each polymerizable composition like a
monomer/oligomer (A1) and (A2), and/or monomer (B) may be different
in each polymerizable composition like a monomer (B1) and a monomer
(B2). Such polymer composition obtained by a polymerizable
composition comprising for example an alternative deposition of a
voxel of polymerizable composition comprising monomer (A1) and
monomer (B1) and a voxel of polymerizable composition comprising
monomer (A2) and monomer (B2), may advantageously presented
optimize properties as refractive index or mechanical properties.
Then it is an embodiment of the invention, wherein voxels comprise
different polymerizable compositions such that some voxels comprise
a first polymerizable composition comprising monomer or oligomer
(A) and monomer (B), and some other voxels comprise a different
polymerizable composition comprising a monomer or oligomer (A') and
monomer (B'), (A') being chemically different than (A), and (B')
being chemically different than (B).
[0138] "Ophthalmic lens", according to the invention, is defined as
lens adapted namely for mounting in eyeglasses whose function is to
protect the eye and/or to correct vision; this lens is selected
from the afocal, unifocal, bifocal, trifocal, and progressive lens.
Then it is understood that ophthalmic lens may be corrective or
un-corrective. Eyeglasses wherein ophthalmic lens will be mounted
could be either traditional frame comprising two distinctive
ophthalmic lenses, one for the right eye and one for the left eye,
or like mask, visor, helmet sight or goggle, wherein one ophthalmic
lens facing simultaneously the right and the left eyes. Ophthalmic
lens manufactures by a method of the invention may be produces with
traditional geometry as a circle or may be produced to be fitted to
the frame intended. The present invention presents a great
advantage to manufacture directly a three-dimensional ophthalmic
lens in accordance with the geometry of the frame for which said
ophthalmic lens is dedicated.
[0139] Ophthalmic lens manufacture in accordance with a method of
the invention can furthermore be functionalized, in a further step
after optionally post-treatment step, by adding at least a
functional coating and/or a functional film. Functionalities may be
added on one face of the ophthalmic lens, or on the two faces of
ophthalmic lens, and on each faces, functionalities may be
identical or different. Among the functionality, it may be
mentioned, as example and without any limitation a functionality
selected from anti-impact, anti-abrasion, anti-soiling,
anti-static, anti-reflective, anti-fog, anti-rain, self-healing,
polarization, tint, photochromic, selective wavelength filter which
could be obtain through an absorption filter or reflective filter.
Such selective wavelength filters are particularly interested to
filter ultraviolet radiation, blue light radiation, or infra-red
radiation for example.
[0140] The functionality may be added by at least one process
selected from dip-coating, spin-coating, spray-coating, vacuum
deposition, transfer process or lamination process. By transfer
process it is understood that functionality is firstly deposited on
a support like a carrier, and then is transferred from said carrier
to said ophthalmic lens through an adhesive layer deposited between
the two elements. Lamination is defined as obtaining a permanent
contact between a film which comprises at least one functionality
as mentioned hereinbefore and the surface of the ophthalmic lens to
be treated, said permanent contact being obtained by the
establishment of a contact between said film and said lens,
followed optionally by a polymerization step or a heating step, in
order to finalize the adhesion and adherence between the two
entities. At the end of this lamination process the assembled film
and the optical lens form one single entity. Usually to lamination
process, glue is present in the interface of the film and the
ophthalmic lens.
[0141] Ophthalmic lens manufacture by a method of the present
invention should present the following characteristics: a high
transparency with an absence of or optionally a very low light
scattering or haze, a high Abbe number of greater than or equal to
30 and preferably of greater than or equal to 35, in order to avoid
chromatic aberrations, a low yellowing index and an absence of
yellowing over time, a good impact strength (in particular
according to the CEN and FDA standards), a good suitability for
various treatments (shock-proof primer, anti-reflective or hard
coating deposition, and the like) and in particular good
suitability for colouring, a glass transition temperature value
preferably of greater than or equal to 65.degree. C. and better
still of greater than 90.degree. C. Haze is the percentage of
transmitted light that, in passing through specimen, deviates from
the incident beam by forward scattering. Only light flux deviating
more than 2.5.degree. on the average is considered to be haze.
[0142] On other word, Haze is a measure of intensity of the
transmitted light that is scattered more than 2.5.degree.. It
appears as a milky, smoky, hazy field when looking through a
packaging material. Low values are a measurement of low "haze". As
haze increases, loss of contrast occurs until the object cannot be
seen. Usually an ophthalmic lens could present a haze level less
than 1.
EXAMPLES
Example 1
[0143] In a first example a polymerizable composition comprised:
3,9-dimethylene-1,5,7,11-tetraoxaspiro[5.5]undecane, (DMSOC) (a
free radically polymerizable expanding monomer as monomer (B))
added to compensate for shrinkage of the other curable components;
2,2 bis[p-(2'-hydroxy-3-methacryloxypropoxyphenyl)] propane,
(bis-GMA(A)), which is the base resin for the optical part to be
manufactured; Triethyleneglycol dimethacrylate (TEGDMA), added as a
low viscosity reactive diluent; N,N'-dimethyl-p-toluidine used as a
free radical accelerator (promoter); and dicumyl peroxide is used
to cure the epoxy and as the free radical catalyst (photoinitiator)
to polymerize the DMSOC and other acrylates, as described in Table
1 below. This formulation, when blended and cured versus a control
not containing the expanding monomer, showed no shrinkage vs. the
control that showed approximately 5% shrinkage due to the low
shrinkage monomers chosen.
TABLE-US-00001 TABLE 1 % by wt. % by wt. Material DMSOC/acrylic
Acrylic Control Bis GMA acrylated epoxy 61.3 72.2 DMSOC expanding
monomer 14.7 -- TEGDMA 20.0 25.0 N,N'-dimethyl-p-toluidine 1.3 1.3
dicumylperoxide 3.0 3.0
Example 2
[0144] In a second example, a polymerizable composition comprises:
at least a first quantity of
3,9-dimethylene-1,5,7,11-tetraoxaspiro[5.5]undecane (DMSOC), (known
to expand 4.3% at room temperature and 7% at a temperature just
below its melting point of 70.degree. C.) as the expanding monomer
(B); to which is added diethyleneglycol bis allylcarbonate (A),
which is the base resin for the manufacture of the optical part and
(known to copolymerize with DMSOC); dicumyl peroxide, as a free
radical photoinitiator used for curing; and
N,N'-dimethyl-p-toluidine as a free radical accelerator, used to
reduce the time and energy needed to reach maximum cure, as
described in Table 2 below. With said blended composition, after
depositing voxels to a desired amount, voxels are partially
polymerized with or without induced diffusion, such as by thermal
diffusion; after which free radical polymerization is induced and
viscosity is unchanged versus that of the control not containing
the expanding monomer which exhibits approximately 14% shrinkage.
The resulting 3D polymer, exhibits good optics and geometry.
TABLE-US-00002 TABLE 2 % by wt. % by wt. Material DMSOC/acrylic
Acrylic Control Allyl diglycolcarbonate 80.4 95.3 DMSOC expanding
monomer 14.9 -- N,N'-dimethyl-p-toluidine 1.3 1.3 Benzoyl peroxide
3.4 3.4
Example 3
[0145] In a third example, a polymerizable composition included: a
first quantity of the bicyclic monomer,
3,9-di(5-norbornene-2,2)-1,5,7,11-tetraoxaspiro(5,5)undecane,
(NSOC), a white crystalline solid expanding monomer (B), with
addition of Diglycidyl ether of bisphenol A epoxy (UVR-6110 from
Dow Chemical) (A1); and with the addition of Bis (3,
4-Epoxycyclohexylmethyl) adipate (UVR-6128 from Dow Chemical) (A2)
as the low shrinkage base monomers for the optical part, with
Omicure BC-120 (Boron trifluoride adduct) and Omicure DDA-5
(Dicyandiamide) as curing agents, as described in Table 3 below.
When blended in a monomer ratio of 49.8% UVR-6110 to 25.5% UVR-6128
to 19.7% NSOC, there was no volume change during cure.
TABLE-US-00003 TABLE 3 % by wt. % by wt. Material NSOC/Epoxy Epoxy
control Diglycidyl ether of bisphenol 49.8 62.9 A (UVR-6110)
Bis(3,4-Epoxycyclohexyl 25.5 32.1 methyl) adipate (UVR-6128) NSOC
expanding monomer 19.7 -- Omicure BC-120 (Boron 2.5 2.5 trifluoride
adduct) Omicure DDA5 2.5 2.5 (Dicyandiamide) Shrinkage (density
change) ~0% 5-10%
Example 4
[0146] In a fourth example a polymerizable composition included:
3,4-Diepoxycylcohexane, the base resin for the optical part to be
manufactured (A1); 5 mol % the expanding monomer
Tetraspiroorthocarbonate, (TETRASOC) (B); 2 mol % of
Triarylsulfoniumhexafluoroantimonate, a cationic photoinitiator to
photo-cure the epoxy; with Cyclohexanol,
4,4'-(1-methylethylidene)bis-, polymer with (chloromethyl)oxirane
(Eppaloy 5001) (A2), the second part of the base resin; as
described in Table 4 below, the co-polymer exhibited no shrinkage
upon polymerization and therefore, the epoxy retained most of its
typical mechanical properties.
TABLE-US-00004 TABLE 4 % by wt. % by wt. Material NSOC/Epoxy Epoxy
control 3,4-Diepoxycyclohexane 73.0 78.0 Cyclohexanol, 4,4'-(1-
20.0 20.0 methylethylidene)bis-, polymer with(chloromethyl)oxirane
(Eppaloy 5001) Tetraspiroorthocarbonate 5.0 -- (TETRASOC)
Triarylsulfonium 2.0 2.0 hexafluoroantimonate Shrinkage (density
change) ~0% ~5%
[0147] The co-polymer exhibited no shrinkage upon polymerization
and therefore, the epoxy retained most of its typical mechanical
properties. Therefore, the present invention is well adapted to
attain the ends and advantages mentioned as well as those that are
inherent therein.
[0148] The particular examples disclosed above are illustrative
only, as the present invention may be modified and practiced in
different but equivalent manners apparent to those skilled in the
art having the benefit of the teachings herein. It is, therefore,
evident that the particular illustrative examples disclosed above
may be altered or modified and all such variations are considered
within the scope of the present invention.
[0149] The various elements or steps according to the disclosed
elements or steps can be combined advantageously or practiced
together in various combinations or sub-combinations of elements or
sequences of steps to increase the efficiency and benefits that can
be obtained from the invention.
[0150] It will be appreciated that one or more of the above
embodiments may be combined with one or more of the other
embodiments, unless explicitly stated otherwise.
[0151] The invention illustratively disclosed herein suitably may
be practiced in the absence of any element or step that is not
specifically disclosed or claimed.
[0152] Furthermore, no limitations are intended to the details of
construction, composition, design, or steps herein shown, other
than as described in the claims.
* * * * *